<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        body{
            display: flex;
            flex-flow: column;
            min-height: 100vh;
        }
        header{
            font-size: 30px;
            font-weight: bold;
            text-align: center;
            margin: 30px auto;
        }
        footer>div{
            max-width: 900px;
            height: 100px;
            line-height: 100px;
            border-bottom: 1px solid rgb(255, 255, 255);
            text-align: center;
            font-size: 30px;
            color: white;
        }
        footer{
            /* 添加内边距：视口的50% - 内部元素宽度的一半 */
            padding: 1em calc(50% - 450px);
            background-color: #333;
            /* 设置系数 */
            flex: 1;
        }

    </style>
</head>
<body>
    <header>大标题</header>
    <img src="./img/h1.webp" alt="">
    <img src="./img/h2.webp" alt="">
    <footer>
        <div class="box1">title</div>
        <div class="box2">content</div>
        <div class="box3">icon</div>
    </footer>
</body>
</html>